The prior art discloses unmanned vehicles having a receiving compartment for transporting one or more shipments. In order to be able to remove a shipment from the receiving compartment, the receiving compartment must be opened. For this purpose, the shipment recipient obtains, for example, a code which can be used by the shipment recipient to prove his authorization to open the receiving compartment with respect to the unmanned vehicle. Although this is convenient for the shipment recipient, there is the risk of the code being intercepted, or if he has sufficient time, being guessed by an attacker, with the result that this is considered to be non-secure, in particular for transporting valuable shipments.